You can checkin from any pin card. As well as a start and end time (once you've checked out) you can add notes to go alongside the visit to serve as a reminder later.
You can either manually checkout or set it to auto checkout when you leave the pin location.
It can be really helpful to keep a record of when you've been to a location. This will add the collective amount of time you spend at a location, number of visits and more all on the pin.